CN1182655C

CN1182655C - Dual membrane filter

Info

Publication number: CN1182655C
Application number: CNB021054991A
Authority: CN
Inventors: 栗原崇宏; 蒲生昌夫; 池田吉宏
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 2001-04-06
Filing date: 2002-04-05
Publication date: 2004-12-29
Anticipated expiration: 2022-04-05
Also published as: CN1380745A; US6731187B2; US20020149446A1; KR100443172B1; KR20020077653A; JP2002368577A

Abstract

A dual mode filter includes a casing substrate on which an input electrode, an output electrode, two ground electrodes, and a relay electrode are provided, first and second filter elements mounted in parallel with each other on the casing substrate, and a cap fixed onto the casing substrate. The first and second filter elements each include a first terminal electrode, a second terminal electrode, a pair of segmented electrodes, a counter electrode, and a third terminal electrode. The first terminal electrode of the first filter element is connected to the input electrode, and the third terminal electrode is connected to one ground electrode. The first terminal electrode of the second filter element is connected to the output electrode, and the third terminal electrode is connected to the other ground electrode. The second terminal electrodes of the first and second filter elements are connected to the relay electrode.

Description

Dual mode filter

Technical field

The present invention relates to a kind of dual mode filter, particularly relate to a kind of surface installing type dual mode filter.

Background technology

In the past, in dual mode filter, what extensively adopt is in the encapsulation of being made up of pedestal and conductivity cover plate, is provided with the structure of filter element.

The structure of in Figure 18, having represented existing well-known dual mode filter.

In this dual mode filter, on pedestal 50, be provided with input electrode 51, output electrode 52 and grounding electrode 53, these electrodes 51～53 are pricked capillus towel shape by the top of pedestal 50 to following formation.On pedestal 50, be formed with the insulating barrier 54 of frame shape.For example as opening in flat 5-25832 number bulletin disclosedly real, filter element 60 is the piezo-electric resonators that a plurality of piezoelectric vibration portion are coupled by relaying electric capacity.Filter element 60 comprises by the

piezoelectric substrate

61,62 with piezoelectric effect, and has dielectric property but do not have the dielectric substrate 63 of piezoelectric effect to engage a formed composite substrate, is provided with

vibration section

64,65 on piezoelectric substrate 61,62.These vibration sections the 64, the 65th, a pair of electrode of cutting apart that on an interarea, is provided with, and between the counter electrode that is provided with of another interarea, produce symmetric mode (S mould) and two kinds of diaphragms of skew symmetry mould (A mould) simultaneously.

On filter element 60, two ends are formed with

terminal electrode

66,67 respectively, on the central portion positive and negative, form the electric capacity that constitutes the relaying capacitance part and take out electrode 68.This electric capacity takes out electrode 68 owing to be formed on the dielectric substrate 63, so can prevent to produce the interference vibration in the relaying capacitance part.The

terminal electrode

66,67 of filter element 60 is connected with output, the

input electrode

51,52 of pedestal 50 respectively by conducting

resinl

69a, 69b, and electric capacity takes out electrode 68 and is connected with the grounding electrode 53 of pedestal 50 by conducting resinl 69c.

After being installed in filter element 60 on the pedestal 50, coating silica gel 70 on filter element 60.Then, conductivity cover plate 71 is bonded on the insulating barrier 54, filter element 60 is covered, and with enclose inside.So just can obtain the surface installing type dual mode filter.

But, in the dual mode filter of described structure,, have the problem that produces the interference vibration by the interference between two vibration sections owing on an element, formed two

vibration sections

64,65.

Figure 19 represents the amplitude response of the dual mode filter of described structure.As can be seen from the figure, because the interference between the

vibration section

64,65 has produced fluctuation R in passband.And the attenuation outside the passband is also less.

In addition, in existing structure,,, and form a composite substrate so it is integrated with

piezoelectric substrate

61,62 and dielectric substrate 63 joints to have to owing on an element, be formed with two vibration sections.Therefore, processing cost height not only, but also the reliability of the electrode of two substrate intersections is reduced.

Summary of the invention

So, the objective of the invention is, provide a kind of and can eliminate the interference vibration that produces owing to the interference between the vibration section, cut down finished cost, and the high dual mode filter of connection reliability.

In order to reach described purpose, the invention of claim 1 provides a kind of dual mode filter, it is characterized in that: comprising: the pedestal that is formed with input electrode, output electrode, grounding electrode and repeater electrode; The the 1st, the 2nd filter element of on described pedestal, laterally installing side by side; And be adhesively fixed on cover plate on the pedestal in order to cover described filter element, the 1st, the 2nd filter element forms the 1st terminal electrode in an end of an interarea of piezoelectric substrate, form the 2nd terminal electrode at pars intermedia, centre position at the two-terminal electrode forms a pair of electrode of cutting apart that is connected with the two-terminal electrode respectively, and on another interarea of described piezoelectric substrate, be formed with by with the described electrode pair of cutting apart to the counter electrode that constitutes dual-vibration portion is set, another end at piezoelectric substrate forms the 3rd terminal electrode that is connected with described counter electrode, the 1st terminal electrode of the 1st filter element and the input electrode of pedestal, the grounding electrode of the 3rd terminal electrode and pedestal, connect by conductive bonding material respectively, the 1st terminal electrode of the 2nd filter element and the output electrode of pedestal, the grounding electrode of the 3rd terminal electrode and pedestal, connect by conductive bonding material respectively, the 2nd terminal electrode of the 1st filter element and the repeater electrode of pedestal, the 2nd terminal electrode of the 2nd filter element and the repeater electrode of pedestal connect by conductive bonding material respectively.

In the present invention, not that two vibration sections are set in an element, but a bimodulus vibration section is set in an element, these two elements are installed separately on pedestal, and interconnect by the repeater electrode of pedestal.Therefore, just there is not the problem that produces the interference vibration by the interference between two vibration sections.

And, integratedly forming a composite substrate owing to there is no need piezoelectric substrate engaged with dielectric substrate, thus can cut down finished cost, nor the problem that exists the reliability of the electrode that makes two substrate intersections to reduce.

Have again,,, can more effectively suppress generation and disturb vibration so can not clamp piezoelectric substrate with grounding electrode in subtend ground because repeater electrode is arranged on the pedestal of isolating with filter element.

As described in claim 2, the 1st, the 2nd filter element be mounted to the 1st terminal electrode, the 2nd terminal electrode and cut apart electrode towards pedestal one side for well.That is to say, counter electrode and the 3rd terminal electrode are mounted to towards upside get final product.

Using conductive bonding material, the 1st terminal electrode of filter element is connected with the input electrode or the output electrode of pedestal, and use conductive bonding material, with under the 2nd terminal electrode and the situation that repeater electrode is connected, with these electrodes when upside (side opposite) with pedestal one side, existence must be with conductive bonding materials such as conducting resinl or scolding tin, be coated in continuously till terminal electrode set above filter element begins to the electrode of pedestal, particularly the 2nd terminal electrode and the such unfavorable factor of difficulty that becomes being connected of repeater electrode.That is to say, be because repeater electrode is arranged on the pars intermedia of filter element, thus nearer apart from the vibration section, when applying a large amount of conductive bonding materials, just might have influence on the vibration section.

In contrast, if with the 1st terminal electrode and the 2nd terminal electrode one side when pedestal one side is installed, by conductive bonding material, the 2nd terminal electrode can be engaged with the repeater electrode opposite of pedestal, thereby, connect simply, connection reliability is also high.

As described in claim 3, the 2nd terminal electrode of the 1st filter element and the 2nd filter element, be arranged on the position of a lateral margin of an interarea of being partial to piezoelectric substrate, and do not make itself and the electrode that on another interarea of piezoelectric substrate, forms constitute subtend, the 1st filter element and the 2nd filter element, its 2nd terminal electrode laterally are arranged on the direction of mutual subtend on the pedestal side by side to well.

With the 2nd terminal electrode when the width face of filter element all forms, the 2nd terminal electrode be connected the counter electrode that is arranged on another interarea and the extraction electrode of the 3rd electrode, clamp to subtend piezoelectric substrate.That is to say,, might produce and disturb vibration in this subtend part.

So, in claim 3, the 2nd terminal electrode is arranged on the position of a lateral margin of an interarea of deflection piezoelectric substrate, make itself and the electrode that on another interarea of piezoelectric substrate, forms not constitute subtend, prevent to produce and disturb vibration.And, by laterally being arranged on the pedestal side by side the 1st and the 2nd filter element each other, make between the 2nd terminal electrode that is provided with in the position of its deflection and constitute subtend, can shorten the length dimension of dual mode filter of the present invention, and also can shorten repeater electrode, also can shorten width dimensions.

Its result can constitute small and exquisite dual mode filter.

As described in claim 4, can make thickness T a, the Tb of the 1st filter element and the 2nd filter element and at least one item among width W a, the Wb different mutually.

The vibrating electrode of filter element be cut apart electrode and with the counter electrode of its subtend, by the vibration between these electrodes, obtain desired filtering characteristic.But, in fact at counter electrode, disturb vibration with being connected between the extraction electrode of cutting apart electrode and terminal electrode also to produce, and cut apart electrode, with the extraction electrode that is connected counter electrode and the 3rd terminal electrode between also produce interference and vibrate.In the interference vibration that this produced is the vibration of thickness mode, is characterized in being easy to generate fluctuation on the main waveform of filter.

So, different mutually by the thickness or at least one item in the width that make the 1st filter element and the 2nd filter element in claim 4, can in each element, make to produce and disturb the frequency of vibration to stagger mutually.Therefore, can prevent to disturb the phase mutual interference between the vibration, compare when being identical, can reduce fluctuation thickness or width setup.

In claim 5, it is characterized in that: the thickness T a of the 1st filter element of claim 4 and the thickness T b of the 2nd filter element, any one feature in the row inequality.

Tb＜Ta＜1.01Tb

0.99Tb＜Ta＜Tb

That is to say, be compressed in 1% by thickness difference, and the resonance frequency shift of each element is controlled in 1% filter element.This be because when the resonance frequency shift of two elements greater than 1% the time, bandwidth ratio (bandwidth/f ₀) can sharply reduce, and the symmetric mode (S mould) that constitutes at two elements, the balance of skew symmetry mould (A mould) also be damaged, and is easy to generate main waveform and bad result such as cut apart.

In claim 6, it is characterized in that: the width W a of the 1st filter element of claim 4 and the width W b of the 2nd filter element, satisfy in the following inequality any one.

Wb＜Wa＜1.05Wb

0.95Wb＜Wa＜Wb

The fluctuation of width mould periodically occurs with the ratio of component thickness with element width, and so-called suitable width dimensions scope also periodically occurs.When the stand out of each filter element being compressed to 5%, can reduce fluctuation effectively with interior and when in its scope, element width being staggered.

As described in claim 7, distance L a1 till also can making from the mid point of cutting apart electrode of the 1st filter element to end of length direction, from described mid point begin till another end of length direction distance L a2, begin the distance L b1 till end of length direction and begin distance L b2 till another end of length direction from the mid point of cutting apart electrode of described the 2nd filter element from described mid point, satisfy any in the following inequality.

0＜|La1-Lb1|＜2t

0＜|La2-Lb2|＜2t

Wherein, t is a bigger side among the 1st, the 2nd filter element thickness T a, the Tb.

The propagating wave of propagating along its length that is produced by vibrating electrode produces reflection at the end face of the short brink of filter element, becomes big fluctuation or parasitic reason and produce to disturb to wait with other vibration.So, in claim 7, the distance till changing from the vibrating electrode of two elements to minor face one side end face, the frequency that can stagger thus and disturb vibration to produce.Owing to can not produce the interference that these disturb vibration,, can reduce fluctuation or parasitic so compare when identical with described distance L a1, La2, Lb1 and Lb2 are set at.

In addition, by changing the ratio of La1: La2 and Lb1: Lb2, can further improve effect.

As described in claim 8, also can make the 1st extraction electrode of the 1st filter element and the distance H a1 between the leement duration direction lateral margin, and the distance H a2 between the 2nd extraction electrode and the leement duration direction lateral margin, respectively and the distance H b1 between the 1st extraction electrode of the 2nd filter element and the leement duration direction lateral margin, and the 2nd extraction electrode different with distance H b2 between the leement duration direction lateral margin.

As mentioned above, when the interference of generation thickness mode was vibrated, the end face generation reflection because of the element long side became big fluctuation or parasitic reason and vibrate generation interference etc. with other.So, by changing the position of two element extraction electrodes, stagger the frequency of the interference vibration that is produced, can prevent that them from producing interference, reduce fluctuation or parasitic.

In claim 9, it is characterized in that: between the width W of distance H a1 and distance H a2, distance H b1 and distance H b2 and the 1st, the 2nd filter element, satisfy following relationship.

0＜|Ha1-Hb1|＜W/4

0＜|Ha2-Hb2|＜W/4

Wherein, W is a side bigger among width W a, the Wb of the 1st, the 2nd filter element.

That is to say that according to the residing position of the extraction electrode of filter element, exist the vibration of lead-in wire to manifest stronger situation and more weak situation, key is to be staggered a bit a little in the lead-in wire position of two elements in the vibration that is caused by lead-in wire manifests not strong zone.Be controlled in the W/4 by departure, can suppress fluctuation effectively extraction electrode.

In claim 10, be make between the 3rd extraction electrode of the 1st filter element and the leement duration direction lateral margin apart from Ja, different with between the 3rd extraction electrode of the 2nd filter element and the leement duration direction lateral margin apart from Jb.

This situation is also the same with claim 8, and the end face generation reflection of element long side is passed through in the interference vibration of thickness mode, becomes big fluctuation or parasitic reason and produce interference etc. with other vibration.So, the position of the 3rd extraction electrode by changing two elements, the frequency of the interference vibration that produced of staggering reduces fluctuation or parasitic.

In claim 11, it is characterized in that:, and between the width W of the 1st, the 2nd filter element, satisfy following relationship apart from Ja and apart from Jb.

0＜|Ja-Jb|＜W/4

The same with claim 9, because of the residing position of the extraction electrode of filter element, exist the vibration of lead-in wire to manifest stronger situation and more weak situation, so importantly staggered a bit in the vibration that is caused by lead-in wire manifests not strong zone a little in the lead-in wire position of two elements.Be controlled in the W/4 by departure, can suppress fluctuation effectively extraction electrode.

In claim 12, it is characterized in that: the 1st, the 2nd extraction electrode and the 3rd extraction electrode of the 1st filter element are formed on the position that positive and negative does not constitute subtend; The the 1st, the 2nd extraction electrode and the 3rd extraction electrode of the 2nd filter element are formed on the position that positive and negative does not constitute subtend; The distance D a of Width between the 1st, the 2nd extraction electrode of the 1st filter element and the 3rd extraction electrode is different with the distance D b of Width between the 1st, the 2nd extraction electrode of the 2nd filter element and the 3rd extraction electrode.

Even connect the extraction electrode of cutting apart electrode and terminal electrode, directly do not constitute subtend with the extraction electrode that is connected counter electrode and terminal electrode, because also can producing, the effect of parasitic capacitance etc. disturb vibration.This vibration is also relevant with thickness, occurs fluctuation on the main waveform of filter easily.Therefore, by change the interval of positive and negative extraction electrode on two elements, the frequency that the described interference vibration of can staggering on two elements produces makes their non-interference, therefore compares when identical with the interval of extraction electrode is set at, and can reduce to fluctuate.

As described in claim 13, pedestal also can be made of the medium that is provided with the laminated construction of a plurality of capacitance electrodes in inside, wherein has at least a capacitance electrode to be connected with repeater electrode, has at least another capacitance electrode to be connected with ground capacity.

In order to adjust filtering characteristic, well-known have connection relaying electric capacity between two bimodulus vibration sections, but in the past because relaying electric capacity is formed on the piezoelectric substrate that becomes one, disturb the reason of vibrating so caused to produce.Therefore, the capacitor of single part is installed on pedestal, can be with it as relaying electric capacity, but increased the position that connects so again, and make the reliability reduction easily.

In contrast to this,,, just can save the connection operation when connecting single part, can also improve reliability ensconcing the inside of pedestal in the relaying electric capacity if picture claim 13 is described.And, owing to be the interior electric capacity of interior plant pedestal, so can prevent to cause short circuit with other circuit.In addition, because pedestal has the area bigger than filter element, thus the subtend area of capacitance electrode can be strengthened arbitrarily, and obtain relaying capacitance value arbitrarily.

As described in claim 14, pedestal also can form square, two diagonal positions at pedestal are provided with input electrode and output electrode, at two remaining diagonal positions two grounding electrodes are set, the 3rd terminal electrode of the 1st filter element is connected with a grounding electrode of pedestal, the 3rd terminal electrode of the 2nd filter element is connected with another grounding electrode of pedestal.

Like this, form outer electrode by four bights at pedestal, can make the compact in size of pedestal, and by input electrode and output electrode are arranged on diagonal position, can reduce the influence of the parasitic capacitance of generation between input and output, strengthen the outer attenuation of passband, and be difficult for causing short circuit between input and the output.

Description of drawings

Fig. 1 is the three-dimensional exploded view of dual mode filter one example of the present invention.

Fig. 2 is the vertical view that removes after the cover plate of dual mode filter shown in Figure 1.

Fig. 3 is the central cross sectional view of dual mode filter shown in Figure 2.

Fig. 4 is along the cutaway view of A-A line among Fig. 3.

Fig. 5 is along the cutaway view of B-B line among Fig. 3.

Fig. 6 is the circuit diagram of dual mode filter shown in Figure 1.

Fig. 7 is the amplitude response figure of dual mode filter shown in Figure 1.

Fig. 8 is amplitude response figure behind the elimination relaying electric capacity from dual mode filter shown in Figure 1.

Fig. 9 is the stereogram of the filter element of the embodiment of the invention 2.

Figure 10 is to use the amplitude response figure of the dual mode filter of the identical filter element of the thickness filter element different with thickness.

Figure 11 is the vertical view of the filter element of the embodiment of the invention 3.

Figure 12 is to use the amplitude response figure of the dual mode filter of the identical filter element of the width filter element different with width.

Figure 13 is the rearview of the filter element of the embodiment of the invention 4.

Figure 14 is to use from cutting apart the mid point of electrode, to the amplitude response figure of the dual mode filter of identical filter element of the distance of length direction end and different filter element.

Figure 15 is the vertical view of the filter element of the embodiment of the invention 5.

Figure 16 is when establishing Ha1=Hb1, Ha2=Hb2, Ja=Jb, Da=Db and the amplitude response figure of the dual mode filter when establishing Ha1 ≠ Hb1, Ha2 ≠ Hb2, Ja ≠ Jb, Da=Db.

Figure 17 is when establishing Ha1=Hb1, Ha2=Hb2, Ja ≠ Jb, Da ≠ Db and the amplitude response figure of the dual mode filter when establishing Ha1 ≠ Hb1, Ha2 ≠ Hb2, Ja ≠ Jb, Da ≠ Db.

Figure 18 is the three-dimensional exploded view of existing dual mode filter one example.

Figure 19 is the amplitude response figure of dual mode filter shown in Figure 180.

Symbol among the figure: 1-pedestal; The 2-input electrode; The 3-output electrode; 4,5-grounding electrode; The 6-repeater electrode; 8,9-capacitance electrode; 10,20-filter element; 11,21-piezoelectric substrate; 12,22-the 1st terminal electrode; 13,23-the 2nd terminal electrode; 14,15,24,25-is cut apart electrode; 16,26-counter electrode; 17,27-the 3rd terminal electrode; 18,28-the 3rd extraction electrode; 19a, 29a-the 1st extraction electrode; 19b, 29b-the 2nd extraction electrode; The 40-cover plate.

Embodiment

Fig. 1～Fig. 6 represents an example of dual mode filter of the present invention.

This dual mode filter is a surface installing type, comprising: insulating properties pedestal 1; 2

filter elements

10,20 that on pedestal 1, are set up in parallel; Be coated in the damping material 30 that silica gel on the

filter element

10,20 etc. is formed; Be adhesively fixed on the pedestal 1 metal cover plate 40 of sealing

filter element

10,20 etc.

In addition, on the pedestal 1 of Fig. 1, represented the projection of the electrode shape of

filter element

10,20 following sides.

Pedestal 1 is that the media ceramic multilayer that will not have piezoelectric property is formed by stacking, and it all forms the rectangle sheet.Two diagonal positions on pedestal 1 are provided with input electrode 2 and output electrode 3, and two diagonal positions remaining are provided with grounding electrode 4,5.4 bights at pedestal 1 are provided with

groove

1a, 1b, 1c and 1d, and electrode 2～5 extends the back side one side of pedestal 1 through these grooves 1a～1d always.Extend the inboard of described electrode 2～5 above pedestal 1, and its medial end 2a～5a constitutes the contact site with

filter element

10,20.

In the upper central portion of pedestal 1, be provided with along the repeater electrode 6 of the band shape of short side direction extension, repeater electrode 6 is connected with the upper end of the through hole electrode 7 that extends to pedestal 1 thickness direction pars intermedia always.As shown in Figure 3, this through hole electrode 7 constitutes by burying conducting resinl underground in the hole set on pedestal 1.

In the inside of pedestal 1, be formed with two capacitance electrodes 8,9.As shown in Figure 4, capacitance electrode 8 is by extending to pedestal 1 two electrode part 8a, 8b of the edge portion of angular direction and the linking part 8c that links these two electrode 8a, 8b are constituted.Electrode part 8a, 8b and in formed

grounding electrode

4,5 conductings of the medial surface of groove 1c, 1d.And, for fear of with through hole electrode 7 conductings, make linking part 8c walk around through hole electrode 7.In addition, as shown in Figure 5, another capacitance electrode 9 has with the 9a of central electrode portion of the bottom conducting of through hole electrode 7 with from two electrode part 9b, the 9cs that angular direction extended of the 9a of this central electrode portion to pedestal 1.These two

electrode part

9b, 9c do not arrive the edge portion of motor seat 1.The electrode part 9b of the electrode part 8a of capacitance electrode 8,8b and capacitance electrode 9,9c constitute subtend by the media ceramic layer, form two relaying capacitor C 1, C2.In addition, though formed two relaying capacitor C 1, C2 in this embodiment, also can only form wherein any one.

Filter element

10,20 all is the resonator that utilizes energy enclosed type thickness shear oscillation mould, and is formed with identical shape.In this embodiment, though the resonance frequency of two

filter elements

10,20 is set for identical frequency, also can set different frequencies for.

Filter element

10,20 comprises the piezoelectric substrate 11,21 that is made of the lamellar piezoelectric ceramic of rectangle (for example metatitanic acid zirconia lead plumbate), an end at an interarea of piezoelectric substrate 11,21 is formed with the 1st terminal electrode 12,22, be formed with the 2nd terminal electrode 13,23 at pars intermedia, be formed with respectively a pair of

electrode

14,15 and 24,25 cut apart that are connected with 22,23 with two-terminal electrode 12,13 in two-terminal electrode 12,13 and 22,23 centre position.Another interarea at piezoelectric substrate 11,21, be formed with and the described

counter electrode

16,26 of cutting apart

electrode

14,15 and 24,25 subtends, be formed with the 3rd terminal electrode 17,27 that is connected with

counter electrode

16,26 by extraction electrode 18,28 in another end of piezoelectric substrate 11,21.In addition, the 3rd terminal electrode 17,27 forms the state with the end face encirclement of piezoelectric substrate 11,21.

In described terminal electrode, the 2nd terminal electrode 13,23 is arranged on the position of a lateral margin of an interarea of being partial to piezoelectric substrate 11,21, make itself and the

counter electrode

16,26 or the 3rd terminal electrode 17,27 that are formed at another interarea of piezoelectric substrate 11,21, the extraction electrode 18,28 that connects two electrodes does not in addition constitute subtend.Therefore,

filter element

10,20 have only constitute the bimodulus vibration section cut apart that

electrode

14,15 and 24,25 is clamped piezoelectric substrate 11,21 with

counter electrode

16,26 and the formation subtend.In addition, as mentioned above, the bimodulus vibration section makes two diaphragms of symmetric mode (S mould) and skew symmetry mould (A mould) produce simultaneously exactly.

As shown in Figure 3, keeping between filter element 10 and the pedestal 1 under the state of institute's fixed gap (oscillation space), the 1st terminal electrode 12 of filter element 10 is fastened on the connecting portion 2a of input electrode 2 by conducting resinl P1, the 2nd terminal electrode 13 is fastened on the end of repeater electrode 6 by conducting resinl P2, and the 3rd terminal electrode 17 is fastened on the connecting portion 5a of grounding electrode 5 by conducting resinl P3.Wherein, the 1st terminal electrode 12 and the 2nd terminal electrode 13 are to connect face-to-face by conducting resinl P1, P2 with respect to input electrode 2 and repeater electrode 6, and the 3rd terminal electrode 17 is that conducting resinl P3 is connected from top coating.Particularly, owing to the 3rd terminal electrode 17 is to form surrounding till the end face of piezoelectric substrate 11, so the connection reliability height.

Equally, the 1st terminal electrode 22 of filter element 20 is fastened on the connecting portion 3a of output electrode 3 by conducting resinl, the 2nd terminal electrode 23 is fastened on by conducting resinl on another end of repeater electrode 6, and the 3rd terminal electrode 27 is fastened on the connecting portion 4a of grounding electrode 4 by conducting resinl.

Like this,, laterally be installed in side by side on the pedestal 1 two

filter elements

10,20, so that cut apart

electrode

14,15,24,25 sides towards pedestal 1 one sides, and make the 2nd terminal electrode 13,23 mutual subtends.Therefore, as shown in figure 18, compare, can shorten the length dimension Lc of pedestal 1 with the dual mode filter that the element that is provided with the length of two vibration sections is installed to the existing structure on the pedestal.In addition, in the present embodiment, two

filter elements

10,20 are set up in parallel under length direction only staggers state apart from S (with reference to Fig. 2), but as long as change the shape of repeater electrode 6, two

filter elements

10,20 are pretty good turned up the soil at length direction be set up in parallel.In this case, can further shorten the length dimension of pedestal 1.

In addition, though the width dimensions Wc of pedestal 1 becomes bigger than conventional example,, also the increase of width dimensions Wc can be restricted to minimum degree by with

filter element

10,20 close settings.

As mentioned above, by two

filter elements

10,20 are installed on the pedestal 1, shown in the circuit diagram of Fig. 6, can obtain comprising the dual mode filter of two bimodulus vibration sections and two relaying capacitor C 1, C2.

On pedestal 1, frame shape ground is formed with the insulating barrier of being made up of for example glass cement etc. 41, and makes it surround the installation portion of filter element 10,20.Be adhesively fixed on this insulating barrier 41 peristome of metal cover plate 40 is sealed inside.Therefore, the intrusion of solder flux or moisture can be prevented, the dual mode filter that reliability is high can be realized.

In addition, the metal cover plate 40 and the

grounding electrode

4 or 5 of pedestal 1 are conducted.In this case, can obtain the dual mode filter of electromagnetic armouring structure.

Fig. 7 represents the amplitude response by the dual mode filter of the above structure.At this, passband central frequency is set at 10.7MHz.

As can be seen from Figure 7, fluctuation does not wait interference waveform in passband, and has obtained the outer attenuation of sufficient passband, has constituted very desirable waveform.

In addition, Fig. 8 is illustrated in the dual mode filter shown in Figure 1, the amplitude response when removing relaying capacitor C 1, C2.

In this case, though the outer attenuation of passband is inferior to the situation of Fig. 7, the fluctuation in the passband does not almost have, and obtains the effect that two

filter elements

10,20 are isolated.

Fig. 9 represents the 1st and the

2nd filter element

10,20 of the embodiment of the invention 2.

This embodiment is with the thickness T a of each

filter element

10,20, Tb slight misalignment a bit.Specifically, be the thickness T a=107.0 μ m that makes element 10, the thickness T b=107.2 μ m of another element 20, and satisfy the 0.99Tb＜Ta＜Tb of claim 5.

At this moment, the resonance frequency of the skew symmetry mould of each filter (A mould) is Fra=10.720MHz, Frb=10.700MHz.

(a) among Figure 10 is when making thickness T a=Tb, (b) is to make Ta=107.0 μ m, the waveform of the filter during Tb=107.2 μ m.

As can be seen from the figure, in (a), in the top wave form of filter, fluctuation is arranged, but fluctuation does not have almost in (b).

And, not only when 0.99Tb＜Ta＜Tb, and when Tb＜Ta＜1.01Tb, also can similarly suppress the generation of fluctuating.

Figure 11 represents the 1st and the

2nd filter element

10,20 of the embodiment of the invention 3.

In embodiment 3, make width W a, the Wb of the 1st filter element 10 and the 2nd filter element 20 different mutually.Specifically, be to make Wa=0.95mm, Wb=0.98mm, satisfy the condition of the 0.95Wb＜Wa＜Wb of claim 7.

(a) among Figure 12 is expression when making width W a=Wb=0.98mm, is to make Wa=0.95mm as embodiment 3 (b), the filter shape during Wb=0.98mm.

And, not only when 0.95Wb＜Wa＜Wb, and when Wb＜Wa＜1.05Wb, also can similarly suppress the generation of fluctuating.

The fluctuation of width mould periodically occurs with the ratio of component thickness and element width, the also periodically appearance of the width dimensions scope that what is called is suitable.When the stand out each filter element is limited in 5%, and when in this scope, element width being staggered, can reduce fluctuation effectively.

In addition, though also can be not according to above-described relational expression, and cooperate with the size of the suitable width dimensions scope that occurs at next cycle, at this moment, will bring the area change of vibrating electrode, maybe need to increase shortcomings such as chip size.For example, if the suitable scope of element width at 0.95mm～1.00mm, its next suitable scope is all selected the width of element 10 and element 20 when 1.20mm～1.25mm in the scope of 0.95mm～1.00mm, and the two is staggered is important.This is because if different therewith, with element 10 in 0.95mm～1.00mm, and when element 20 selected in 1.20mm～1.25mm, owing to bring chip size to increase, or vibrating electrode area difference, just be easy to generate in the balance of two symmetric mode that element constituted (S mould), skew symmetry mould (A mould) destroyedly, main waveform such as is cut apart at adverse consequences.

Figure 13 represents the 1st and the

2nd filter element

10,20 of the embodiment of the invention 4.

In this embodiment, the distance L a1 till making from the mid point of cutting apart

electrode

14,15 of the 1st filter element 10 to end of length direction respectively, from described mid point begin till another end of length direction distance L a2, till from the mid point of cutting apart

electrode

24,25 of the 2nd filter element 20 to end of length direction distance L b1, begin distance L b2 difference till another end of length direction from described mid point.Specifically, make La1=0.60mm, La2=1.90mm, Lb1=0.65mm, Lb2=1.85mm exactly.Wherein, in the thickness of each

filter element

10,20, a side's that will be bigger value is as t (Tb=107.2 μ m).

This satisfies claim 7

0＜|La1-Lb1|＜2t

0＜|La2-Lb2|＜2t

Condition.

Figure 14 (a) makes La1=Lb1, La2=Lb2, just makes La1: La2=Lb1: during Lb2, (b) be filter shape when making La1=0.60mm, La2=1.90mm, Lb1=0.65mm, Lb2=1.85mm as embodiment 4.

As can be seen from the figure, in (a) median filter top wave form, have fluctuation, but fluctuation does not have almost in (b).And, also reduced the parasitism of front end.

Particularly make effect become big by the ratio that changes La1: La2 and Lb1: Lb2.

Figure 15 represents the 1st and the

2nd filter element

10,20 of the embodiment of the invention 5.

In embodiment 5, be the 1st extraction electrode 19a and the beeline Ha1 of leement duration direction lateral margin and the beeline Ha2 of the 2nd extraction electrode 19b and leement duration direction lateral margin that makes the 1st filter element 10, beeline Hb2 with the beeline Hb1 of the 1st extraction electrode 29a of the 2nd filter element 20 and leement duration direction lateral margin and the 2nd extraction electrode 29b and leement duration direction lateral margin is different respectively, or make the 3rd extraction electrode 18 of the 1st filter element 10 and the beeline Ja of leement duration direction lateral margin, different with the 3rd extraction electrode 28 of the 2nd filter element 20 with the beeline Jb of leement duration direction lateral margin, or make the 1st extraction electrode 19a of the 1st filter element 10 and the distance D a of the 3rd extraction electrode 18, different with the distance D b of the 1st extraction electrode 29a of the 2nd filter element 20 and the 3rd extraction electrode 28.But, make the 1st filter element 10 identical, and make the width of the width of the width of the 1st extraction electrode separately, the 2nd extraction electrode separately and the 3rd extraction electrode separately identical with the width of the 2nd filter element 20.

Specifically, make Ha1=Ha2=0.30mm, Hb1=Hb2=0.35mm, Ja=0.05mm, Jb=0.10mm.At this moment, make element width Wa, the Wb of

filter element

10,20 be 1.00mm, the thickness of extraction electrode is designed to 0.15mm.At this moment, the interval D a=0.35mm of the positive and negative extraction electrode of filter element 10, the interval D b=0.25mm of the positive and negative extraction electrode of filter element 20.

In the above constitutes, Hb-Ha=0.05mm, Jb-Ja=0.05mm, satisfy 0 respectively＜| Ha-Hb|＜W/4,0＜| Ja-Jb|＜W/4.

(a) of Figure 16 is when making Ha1=Hb1, Ha2=Hb2, Ja=Jb, Da=Db, (b) being that (a) of Figure 17 is when making Ha1=Hb1, Ha2=Hb2, Ja ≠ Jb, Da ≠ Db when making Ha1 ≠ Hb1, Ha2 ≠ Hb2, Ja ≠ Jb, Da=Db, (b) is each filter shape when making Ha1 ≠ Hb1, Ha2 ≠ Hb2, Ja ≠ Jb, Da ≠ Db.Above-described object lesson be equivalent to Figure 17's (b).

As can be seen from the figure, in Figure 16 (a) median filter top wave form, fluctuation is arranged, but at (a) of Figure 16 (b), Figure 17 and almost not fluctuation (b).Particularly the top wave form of Figure 17 (b) is the most desirable.

In described embodiment, though used the filter element that utilizes thickness shear oscillation mould, be not limited thereto as filter element, also can use thickness lengthwise oscillations mould etc., utilize the filter element of other vibrations.

But, under the situation of the filter element that utilizes thickness shear oscillation mould, owing to can reduce its width dimensions, so when two filter elements laterally were set up in parallel, the effect of width dimensions Wc that can shorten pedestal was big.

In addition, the present invention be not limited to two transversely arranged shapes of filter element be set up in parallel, can arrange vertically also that shape ground is in upright arrangement to be provided with.

By above explanation as can be known, according to the invention of claim 1, owing to will comprise that two filter elements of independent bimodulus vibration section are installed separately on pedestal, and be connected with the electrode of pedestal, so can prevent two interference between the vibration section, can prevent to produce to disturb and vibrate.

In addition, because as long as make two small-sized filter elements respectively, and install them on the pedestal and get final product, so compare with the existing dual mode filter that piezoelectric substrate and dielectric substrate is engaged a composite base plate of integrated formation, can cut down finished cost, and also not have the problem of the reliability reduction of the electrode that makes two substrate intersections.

In addition, because relaying electric capacity is formed on the pedestal of isolating with filter element,, can suppress to disturb generation of vibration effectively so can not clamp piezoelectric substrate with grounding electrode in subtend ground.

Claims

1. a dual mode filter is characterized in that,

Comprise:

Be formed with the pedestal of input electrode, output electrode, grounding electrode and repeater electrode;

The the 1st, the 2nd filter element of on described pedestal, laterally installing side by side; And

Be fixed on cover plate on the pedestal in order to cover described filter element by bonding way,

1st, the 2nd filter element forms the 1st terminal electrode in an end of an interarea of piezoelectric substrate, form the 2nd terminal electrode at pars intermedia, centre position at the two-terminal electrode forms a pair of electrode of cutting apart that is connected with the two-terminal electrode respectively, and on another interarea of described piezoelectric substrate, form by with the described electrode pair of cutting apart to the counter electrode that constitutes the bimodulus vibration section is set, another end at piezoelectric substrate forms the 3rd terminal electrode that is connected with described counter electrode

The grounding electrode of the 1st terminal electrode of the 1st filter element and the input electrode of pedestal, the 3rd terminal electrode and pedestal connects by conductive bonding material respectively,

The grounding electrode of the 1st terminal electrode of the 2nd filter element and the output electrode of pedestal, the 3rd terminal electrode and pedestal connects by conductive bonding material respectively,

The 2nd terminal electrode of the 1st filter element and the repeater electrode of pedestal, the 2nd terminal electrode of the 2nd filter element and the repeater electrode of pedestal connect by conductive bonding material respectively.

2. dual mode filter according to claim 1 is characterized in that, described the 1st, the 2nd filter element is mounted to and makes its 1st terminal electrode, the 2nd terminal electrode and cut apart electrode towards pedestal one side.

3. dual mode filter according to claim 1, it is characterized in that, the 2nd terminal electrode of described the 1st filter element and the 2nd filter element, be arranged on the position of a lateral margin of an interarea of being partial to piezoelectric substrate, and make itself and the electrode that on another interarea of piezoelectric substrate, forms not constitute subtend

Described the 1st filter element and the 2nd filter element, its 2nd terminal electrode laterally is arranged on the pedestal on the direction of mutual subtend side by side.

4. dual mode filter according to claim 1 is characterized in that, at least one side is different mutually between thickness T a, the Tb of described the 1st filter element and the 2nd filter element and width W a, the Wb.

5. dual mode filter according to claim 4 is characterized in that, the thickness T b of the thickness T a of described the 1st filter element and the 2nd filter element satisfies in the following inequality any one:

Tb＜Ta＜1.01?Tb

0.99Tb＜Ta＜Tb。

6. according to claim 4 or 5 described dual mode filters, it is characterized in that the width W b of the width W a of described the 1st filter element and the 2nd filter element satisfies in the following inequality any one:

Wb＜Wa＜1.05Wb

0.95Wb＜Wa＜Wb。

7. dual mode filter according to claim 1, it is characterized in that, from the mid point of cutting apart electrode of described the 1st filter element begin till end of length direction distance L a1, from described mid point begin till another end of length direction distance L a2, begin the distance L b1 till end of length direction and begin distance L b2 till another end of length direction from the mid point of cutting apart electrode of described the 2nd filter element from described mid point, satisfy following inequality:

0＜|La1-Lb1|＜2t

0＜|La2-Lb2|＜2t

8. dual mode filter according to claim 1; It is characterized in that; The 1st terminal electrode of described the 1st, the 2nd filter element and a side's the 1st thinner extraction electrode of width that electrode extends by the length direction at element of cutting apart is connected; The 2nd terminal electrode and the opposing party's the 2nd thinner extraction electrode of width that electrode extends by the length direction at element of cutting apart is connected; Counter electrode and the 3rd electrode are connected by the 3rd thinner extraction electrode of width that the length direction at element extends

Beeline Ha1 between the 1st extraction electrode of described the 1st filter element and the leement duration direction lateral margin, and the beeline Ha2 between the 2nd extraction electrode and the leement duration direction lateral margin, respectively and the beeline Hb1 between the 1st extraction electrode of the 2nd filter element and the leement duration direction lateral margin, and the 2nd extraction electrode different with beeline Hb2 between the leement duration direction lateral margin.

9. dual mode filter according to claim 8 is characterized in that, between the width W of described distance H a1 and distance H a2, described distance H b1 and distance H b2 and described the 1st, the 2nd filter element, satisfies following relationship:

0＜|Ha1-Hb1|＜W/4

0＜| Ha2-Hb2|＜W/4 wherein, W is a side bigger among width W a, the Wb of the 1st, the 2nd filter element.

10. dual mode filter according to claim 1; It is characterized in that; The 1st terminal electrode of described the 1st, the 2nd filter element and a side's the 1st thinner extraction electrode of width that electrode extends by the length direction at element of cutting apart is connected; The 2nd terminal electrode and the opposing party's the 2nd thinner extraction electrode of width that electrode extends by the length direction at element of cutting apart is connected; Counter electrode and the 3rd electrode are connected by the 3rd thinner extraction electrode of width that the length direction at element extends

Beeline Ja between the 3rd extraction electrode of described the 1st filter element and the leement duration direction lateral margin is different with the beeline Jb between the leement duration direction lateral margin with the 3rd extraction electrode of the 2nd filter element.

11. dual mode filter according to claim 10 is characterized in that, and is described apart from Ja and apart from Jb, and between the width W of the 1st, the 2nd filter element, satisfies following relationship:

0＜|Ja-Jb|＜W/4

12. dual mode filter according to claim 1; It is characterized in that; The 1st terminal electrode of described the 1st, the 2nd filter element and a side's the 1st thinner extraction electrode of width that electrode extends by the length direction at element of cutting apart is connected; The 2nd terminal electrode and the opposing party's the 2nd thinner extraction electrode of width that electrode extends by the length direction at element of cutting apart is connected; Counter electrode and the 3rd electrode are connected by the 3rd thinner extraction electrode of width that the length direction at element extends

The the 1st, the 2nd extraction electrode and the 3rd extraction electrode of described the 1st filter element are formed on the position that positive and negative does not constitute subtend,

The the 1st, the 2nd extraction electrode and the 3rd extraction electrode of described the 2nd filter element are formed on the position that positive and negative does not constitute subtend,

The distance D a of Width between the 1st, the 2nd extraction electrode of the 1st filter element and the 3rd extraction electrode is different with the distance D b of Width between the 1st, the 2nd extraction electrode of the 2nd filter element and the 3rd extraction electrode.

13. dual mode filter according to claim 1 is characterized in that, described pedestal forms rectangle,

Two diagonal positions at pedestal are provided with input electrode and output electrode,

At two remaining diagonal positions two grounding electrodes are set,

The 3rd terminal electrode of the 1st filter element is connected with a grounding electrode of pedestal,

The 3rd terminal electrode of the 2nd filter element is connected with another grounding electrode of pedestal.